<b>Objective:</b> To determine whether patients previously diag-nosed as chronic fatigue syndrome (CFS) actually have primary haemochomatosis (PH).
<b>Methods:</b> The setting was a Dutch referral centre. Transferrin saturation (TS) was retrospectively evaluated in banked blood samples of 88 patients diagnosed as CFS. Patients with elevated TS values were asked to provide a new overnight fasting blood sample for a second determination of TS and measurement of serum ferritin. The DNA was inves-tigated for mutations in the HFE gene when one of these iron parameters was elevated.
<b>Results:</b> For 19 out of 88 patients with CFS an elevated TS was found. A new blood sample was obtained from 11 of these 19: six had increased TS and two had elevated serum ferritin values. These eight patients were neither C282Y homozygotes nor compound C282Y-H63D heterozygotes. In the eight cases where no new blood samples could be obtained, the TS was >50% for two of the five men and <45% for the three female patients.
<b>Conclusion:</b> In a group of 88 CFS patients we could exclude PH in all but two of them (prevalence 2.3%; 95% confidence interval 0-5.5%). In our population of CFS patients PH is not more common than in a control population of northern European descent (prevalence 0.25-0.50%).